CN111321477A

CN111321477A - SnX2Nanofiber material, preparation method, negative electrode active material, negative electrode, secondary battery or capacitor and preparation method thereof

Info

Publication number: CN111321477A
Application number: CN201811551381.7A
Authority: CN
Inventors: 唐永炳; 周继伟; 周小龙
Original assignee: Shenzhen Institute of Advanced Technology of CAS
Current assignee: Shenzhen Institute of Advanced Technology of CAS
Priority date: 2018-12-17
Filing date: 2018-12-17
Publication date: 2020-06-23
Anticipated expiration: 2038-12-17
Also published as: CN111321477B

Abstract

The invention belongs to the technical field of energy, and relates to a SnX₂Nanofiber materials, methods of making, negative electrode active materials, negative electrodes, secondary batteries or capacitors, and methods of making the same. SnX₂A method of preparing a nanofiber material, wherein X is a halogen element, the method comprising: SnX₂Mixing the solution with a polymer solution to obtain a polymer gel solution, and preparing SnX by using an electrostatic spinning mode₂A nanofiber material. The nanofiber material can be used as a negative electrode active material to be applied to a secondary battery or a capacitor. The invention utilizes the electrostatic spinning technology to prepare SnX₂The nanofiber material is used for carrying out structural design and modification treatment on the cathode active material to prepare the polymer nanofiber with excellent surface function and good mechanical property, and the problems of unstable structure, poor circulation stability, more side reactions between the material and electrolyte, low ionic and electronic conductivity and the like of the existing cathode active material of a secondary battery or a capacitor are solved.

Description

SnX2Nanofiber material, preparation method, negative electrode active material, negative electrode, secondary battery or capacitor and preparation method thereof

Technical Field

The invention belongs to the technical field of energy, and particularly relates to SnX₂Nanofiber materials, methods of making, negative electrode active materials, negative electrodes, secondary batteries or capacitors, and methods of making the same.

Background

In the field of energy, the secondary battery has been widely studied in the industry because it can be repeatedly charged and discharged, can reduce the use cost, and has little environmental pollution. The emergence of secondary batteries has catered for and accelerated the development trend of the modern electronic information industry towards portability and miniaturization. The secondary battery has excellent performances such as high open-circuit voltage, large energy density, small self-discharge rate, long service life, no memory effect, no pollution and the like, and is widely applied to portable consumer electronics products such as mobile phones, notebook computers, digital cameras, MP3 and the like. Secondary batteries have been largely successful in terms of yield and market size.

However, the development of the battery is still very slow compared to the update speed of the electronic information industry, and the demand for a battery with high energy density, high power density, good stability and excellent cycle performance is still very urgent. Representative components constituting the secondary battery include a positive electrode, a negative electrode, an electrolyte, a separator, and the like, and the negative electrode generally includes a negative electrode current collector and a negative electrode active material. The negative active material is very critical to the performance requirements of the secondary battery on high capacity and high cycle performance. Therefore, it is necessary to provide a structure-stable anode active material and a method for preparing the same, so that the anode active material is usedThe negative electrode of the material, and a secondary battery or a capacitor have high capacity and high cycle performance. The tin-based material used as one of the negative electrode materials of the secondary battery has high theoretical energy density and high theoretical specific capacity which is about 2-3 times of graphite (Sn: 994 mAh.g)^－1，SnO：876mAh·g^－1，SnO₂：780mAh·g^－1VS graphite 372mAh g^－1) Thereby arousing the wide attention of people. However, during repeated insertion/extraction, the cycle performance is poor due to particle aggregation due to large specific volume change, and during charge and discharge, the electrode polarization is caused by volume expansion caused by alloying/dealloying reaction between metal and tin, thereby reducing the conduction path between electrode materials and the contact with a current collector, resulting in rapid capacity fade. In view of the above problems, researchers have proposed strategies to improve the structural stability of materials by changing the shape, size, porosity, etc. of electrode materials. In addition, the tin-based nanofiber material prepared based on the electrostatic spinning technology can be mixed with a conductive additive to be used as a negative electrode active material of a secondary battery, and has high capacity and high cycle stability.

However, synthesis of SnO according to existing electrostatic spinning₂The related report of the composite nanofiber material of/Sn shows that SnO₂As a negative electrode active material for a secondary battery, although having a high theoretical capacity, a metal oxide is formed on the negative electrode with an electrolyte containing a metal salt, for example, SnO in a sodium ion battery₂Reacts with sodium salt in the electrolyte to form Na₂O diffuses to the surface of the negative electrode, and irreversible phase change occurs, so that the phenomenon of rapid capacity attenuation occurs.

In view of this, the invention is particularly proposed.

Disclosure of Invention

An object of the present invention is to provide a SnX₂The preparation method of the nanofiber material, wherein X is a halogen element, has simple process and is easy to implementThe cost is low, the prepared material has excellent surface function and good mechanical property, and the problems can be overcome or the technical problems can be at least partially solved.

The invention also aims to provide a SnX prepared by the method₂SnX prepared by preparation method of nanofiber material₂The nanofiber material has the characteristics of excellent surface function, good mechanical property, stable structure and the like, and can endow the battery with the characteristics of good circulation stability, less side reaction between the material and electrolyte, higher ionic and electronic conductivity and the like when being applied to the battery.

Another object of the present invention is to provide a SnX₂Use of nanofiber materials as negative active materials in secondary batteries or capacitors.

Still another object of the present invention is to provide an anode active material; a negative electrode; a secondary battery or capacitor; a method for manufacturing a secondary battery or a capacitor. Using the above-mentioned SnX₂The negative electrode active material, negative electrode, secondary battery or capacitor of the nanofiber material has a high capacity, can maintain a stable voltage, and exhibits excellent cycle stability.

In order to achieve the purpose, the invention adopts the technical scheme that:

according to one aspect of the invention, the invention provides an SnX₂Method for preparing nano-fiber material, SnX₂Wherein X is a halogen element, said process comprising the steps of:

SnX₂Mixing the solution with a polymer solution to obtain a polymer gel solution, and preparing SnX by using an electrostatic spinning mode₂A nanofiber material;

preferably, said X is F, Cl or Br, preferably F.

As a further preferable technical scheme, the SnX₂The solvent in the solution is a mixed solvent composed of an organic solvent and water, preferably the organic solvent comprises at least one of alcohols, ketones, esters or ethers, more preferably the organic solvent is an alcohol organic solvent, more preferably the alcohol is a lower alcohol, and more preferably the organic solvent is an alcohol organic solventThe lower alcohol comprises at least one of methanol, ethanol, propanol, ethylene glycol or butanol, and preferably the lower alcohol is ethanol;

preferably, the mass ratio of the organic solvent to the water is 1-10: 1, preferably 2-4: 1;

preferably, SnX₂SnX in solution₂The concentration range of (A) is 0.05-15 g/mL, preferably 0.1-10 g/mL;

preferably, SnX₂The solution also contains inorganic salts including NaCl, KCl, LiCl, and FeCl₃、ZnCl₂、CuCl₂Or NaNO₃Preferably NaCl; preferably, the inorganic salt is with SnX₂The mass ratio of (A) to (B) is 0.01-0.5: 1, preferably 0.05-0.1: 1;

preferably, SnX₂Carrying out ultrasonic dispersion in the solution preparation process, wherein the ultrasonic dispersion time is 5-60 min;

preferably, in the polymer solution, the polymer is a polymer which is soluble in both water and an organic solvent, preferably the polymer comprises at least one of polyacrylonitrile, polyvinylpyrrolidone, polyethylene oxide or polyvinyl alcohol, and further preferably polyvinylpyrrolidone;

preferably, the concentration of the polymer in the polymer solution is in the range of 0.01-20 g/mL, preferably 0.1-10 g/mL.

According to a further preferable technical scheme, in the electrostatic spinning process, the voltage is 10-25 kV, and preferably 15-22 kV;

and/or in the electrostatic spinning process, the solution feeding rate is 0.1-10 mL/h, preferably 0.2-1.0 mL/h;

and/or in the electrostatic spinning process, the distance between the spray head and the collector is 10-20 cm, preferably 12-15 cm;

and/or in the electrostatic spinning process, the material of the collector is at least one of aluminum, copper, tin, zinc or lead, and preferably copper foil;

preferably, the electrostatic spinning is followed by the steps of separating, washing and drying;

preferably, the separating comprises at least one of centrifugation, sonication and filtration.

According to another aspect of the invention, the invention provides a SnX composed of the above₂SnX prepared by preparation method of nanofiber material₂A nanofiber material.

According to another aspect of the invention, the invention provides a method for controlling the SnX₂SnX obtained by preparation method of nanofiber material₂Nanofiber material or said SnX₂Use of nanofiber materials as negative active materials in secondary batteries or capacitors.

According to another aspect of the present invention, there is provided a negative active material comprising the SnX described above₂SnX obtained by preparation method of nanofiber material₂Nanofiber material or SnX described above₂A nanofiber material.

As a further preferable technical solution, the negative active material further includes a conductive additive;

preferably, the conductive additive is a carbon material, preferably the carbon material comprises at least one of acetylene black, activated carbon, mesocarbon microbeads graphite, natural graphite, expanded graphite, glassy carbon, carbon-carbon composite material, carbon fiber, hard carbon, porous carbon, highly oriented graphite, carbon black, carbon nanotubes or graphene, and further preferably the carbon material is acetylene black;

preferably, in the anode active material, SnX₂The content of the nanofiber material is 50-99% of the total mass of the negative active material, and preferably 60-80%.

According to another aspect of the present invention, there is provided a negative electrode comprising a negative electrode current collector and a negative electrode material, the negative electrode material comprising the negative electrode active material described above;

preferably, the negative electrode material comprises 60-97 wt% of negative electrode active material, 1-25 wt% of conductive agent and 2-15 wt% of binder;

preferably, the conductive agent comprises at least one of conductive carbon black, conductive carbon spheres, conductive graphite, carbon nanotubes, conductive carbon fibers, graphene or reduced graphene oxide;

preferably, the binder comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl cellulose, SBR rubber, or a polyolefin-based binder.

Preferably, the negative current collector is a metal selected from any one of aluminum, copper, tin, zinc, lead, antimony, cadmium, gold, bismuth and germanium; or the negative current collector is an alloy at least containing any one of aluminum, copper, tin, zinc, lead, antimony, cadmium, gold, bismuth or germanium; or the negative current collector is a metal compound at least containing any one of aluminum, copper, tin, zinc, lead, antimony, cadmium, gold, bismuth or germanium; preferably, the negative electrode current collector is a copper foil.

According to another aspect of the present invention, there is provided a secondary battery or capacitor comprising the negative electrode, the positive electrode, the separator interposed between the negative electrode and the positive electrode, and an electrolytic solution as described above;

preferably, the secondary battery is a lithium ion battery, a sodium ion battery, a potassium ion battery, a calcium ion battery, a magnesium ion battery or a zinc ion battery;

or the secondary battery is a lithium-based dual-ion battery, a sodium-based dual-ion battery, a potassium-based dual-ion battery, a calcium-based dual-ion battery, a magnesium-based dual-ion battery or a zinc-based dual-ion battery;

preferably, the capacitor is a lithium ion capacitor, a sodium ion capacitor, a potassium ion capacitor, a calcium ion capacitor, a magnesium ion capacitor or a zinc ion capacitor;

or the capacitor is a lithium ion hybrid super capacitor, a sodium ion hybrid super capacitor, a potassium ion hybrid super capacitor, a calcium ion hybrid super capacitor, a magnesium ion hybrid super capacitor or a zinc ion hybrid super capacitor.

According to another aspect of the present invention, there is provided a method for manufacturing a secondary battery or capacitor, comprising assembling the negative electrode, the electrolyte, the separator, and the positive electrode as described above to obtain a secondary battery;

alternatively, a capacitor is obtained by assembling the negative electrode, the electrolyte, the separator, and the positive electrode as described above.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention utilizes SnX prepared by electrostatic spinning₂The nanofiber material, namely the stannous halide nanofiber material can be used as a negative electrode active material of a secondary battery or a capacitor, has higher capacity, can maintain stable voltage, shows excellent cycle stability, effectively inhibits side reaction between the material and electrolyte, obviously improves the ionic and electronic conductivity, widens the selection range of the negative electrode material of the secondary battery or the capacitor, and realizes the development and expansion of high-valued application of the polymer nanofiber material.

2. The invention utilizes the electrostatic spinning technology to prepare SnX₂The nanofiber material is used for carrying out structural design and modification treatment on the cathode active material to prepare the polymer nanofiber with excellent surface function and better mechanical property, so that the problems of unstable structure, poor circulation stability, more side reactions between the material and electrolyte, low ionic and electronic conductivity and the like of the existing cathode active material of a secondary battery or a capacitor are solved.

3. The preparation method disclosed by the invention is simple to operate, scientific and reasonable, easy to implement, low in cost, strong in operability and easy to realize large-scale industrial production.

4. The cathode, the secondary battery or the capacitor using the cathode active material has higher capacity, can maintain stable voltage and has good cycling stability.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 shows SnX according to an embodiment of the present invention₂Electrostatic spinning of nanofiber materialsA schematic process principle;

fig. 2 is a schematic structural view of a secondary battery according to an embodiment of the present invention.

Icon: 10-a high voltage power supply; 20-polymer solution; 30-Taylor cone; 40-a metal collector; 1-negative current collector; 2-a negative active material; 3-an electrolyte; 4-a separator; 5-positive electrode active material; 6-positive electrode current collector.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to embodiments and examples, but those skilled in the art will understand that the following embodiments and examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Those who do not specify the conditions are performed according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

In a first aspect, there is provided in at least one embodiment an SnX₂Method for preparing nano-fiber material, SnX₂Wherein X is a halogen element, said process comprising the steps of:

SnX₂Mixing the solution with a polymer solution to obtain a polymer gel solution, and preparing SnX by using an electrostatic spinning mode₂A nanofiber material.

In the prior art, Narsimulu et al use the starting material SnCl₂·2H₂O electrospinning to Sn/SnO₂The diameter of the composite nano fiber can be regulated from nanometer to micron, polyvinyl alcohol (PVA) is adopted as a polymer and a carbon source, electrostatic spinning conditions are set, and high-pore carbon (Sn-SnO) is interconnected in three dimensions₂/C) encapsulating Sn and SnO in composite nanofiber₂And (3) nanoparticles. However, the existing tin-based composite nanofiber material is easy to cause the phenomenon of capacity rapid attenuation, the application range is limited, and the surface function and the mechanical property need to be improved.

Based on the above, in order to avoid the defects of the prior art, the invention provides a method for preparing SnX by adopting an electrostatic spinning process₂Method for polymerizing nanofibers by pairing SnX₂The surface modification develops a negative electrode nano fiber material suitable for batteries such as lithium, sodium, potassium, calcium, magnesium, zinc and the like and corresponding capacitors thereof, comprises a negative electrode active material and a negative electrode prepared from the nano fiber material, and is further assembled to form a secondary battery and the corresponding capacitor. Thus, the SnX of the invention₂The nano-fiber material is not only suitable for lithium ion secondary batteries, but also suitable for various novel batteries and capacitors such as sodium, potassium, calcium, magnesium, zinc and the like, greatly relieves the pressure of lithium resource shortage, reduces the cost and lightens the influence of the batteries or the capacitors on the environment.

At present, related to SnX₂No reports have been found on the work of electrospinning into polymer nanofibers. The invention uses the electrostatic spinning technology to prepare SnX₂The nano-fiber widens the selection range of the battery cathode material, and the electrostatic spinning is carried out on the cathode active material SnX₂Structural design and modification treatment are carried out to prepare SnX₂The polymer nanofiber has surface functional flexibility and better mechanical properties. Further SnX₂The nanofiber can be used as a negative electrode active material of a secondary battery and a capacitor, has higher capacity, can maintain stable voltage, shows excellent cycling stability, effectively inhibits side reaction between the material and an electrolyte, and obviously improves the ionic and electronic conductivity.

It is understood that the above-mentioned SnX₂X in the nano-fiber is halogen element, SnX₂May be referred to as stannous halide, and there is no particular limitation on the specific type of X as long as it does not limit the object of the present invention.

In a preferred embodiment, said X is F, Cl or Br, preferably F.

According to the invention, X comprises F, Cl or Br, the above-mentioned SnX₂The nanofibers can be represented as SnF₂(stannous fluoride), SnCl₂(stannous chloride) or SnBr₂(stannous bromide). It should be understood that SnF₂、SnCl₂And SnBr₂Can be used as a negative active material and applied to a secondary battery or a capacitor, and the SnF is mainly used below₂Further details are given by way of example, but this should not be construed as limiting the invention, the remaining stannous halides likewise having similar properties or performance.

In a second aspect, there is provided in at least one embodiment an SnX as described above₂SnX prepared by preparation method of nanofiber material₂A nanofiber material.

In a third aspect, in at least one embodiment, there is provided a SnX device as described₂SnX obtained by preparation method of nanofiber material₂Nanofiber material or said SnX₂Use of nanofiber materials as negative active materials in secondary batteries or capacitors.

In a fourth aspect, there is provided in at least one embodiment an anode active material comprising SnX₂The nanofiber material, wherein X is a halogen element, preferably F, Cl or Br, and more preferably F.

The negative active material of the invention comprises SnX₂The nanofiber material has higher capacity, can maintain stable voltage, shows excellent cycling stability, effectively inhibits side reaction between the material and electrolyte, obviously improves the ionic and electronic conductivity, not only widens the selection range of the cathode material of a secondary battery or a capacitor, but also realizes the development and expansion of high-value application of the polymer nanofiber material.

In a preferred embodiment, the negative active material further includes a conductive additive;

preferably, in the anode active material, SnX₂The mass ratio of the nanofiber material to the conductive additive is 1-100: 1, preferably 2-4: 1, more preferably 3: 1, typically but not limited to, for example, 1: 1. 2: 1. 3: 1. 4: 1. 5: 1. 6: 1. 7: 1. 8: 1. 9: 1. 10: 1. 20: 1. 30: 1. 40: 1. 50: 1. 80: 1. 90: 1 or 100: 1.

the negative electrode active material of the present invention may be SnX alone₂The nanofiber material may also be SnX₂A mixture of a nanofiber material and a conductive additive. With SnX₂When the nano-fiber is mixed with the graphite carbon material conductive additive, the nano-size effect of the material is utilized to increase the dielectric loss of the composite nano-fiber, further reduce the battery impedance and improve the cycle stability.

Further, SnX₂When the nano-fiber and the carbon material conductive additive are mixed to be used as a nano-composite material and used as a negative electrode active material of a secondary battery or a capacitor, the selected carbon material can be at least one of high-conductivity acetylene black, activated carbon, mesocarbon microspherical graphite, natural graphite, expanded graphite, glassy carbon, a carbon-carbon composite material, carbon fiber, hard carbon, porous carbon, high-orientation graphite, carbon black, carbon nano-tubes or graphene and the like; acetylene black is preferred. The anode active material is SnX₂SnX in the case of composite material of nanofiber and carbon material conductive additive₂The content of the nano-fiber may be 50 to 99 wt%, preferably 60 to 80 wt% of the total weight of the negative active material.

A method for preparing an anode active material, comprising the steps of:

SnX₂Mixing the solution with the polymer solution to obtain polymer gel solution, and preparing SnX by using electrostatic spinning technology₂A nanofiber material;

SnX₂The nanofiber material is mixed with an optional conductive additive to obtain the negative active material.

The invention provides a novel SnX by utilizing an electrostatic spinning technology to design and modify the mechanical structure of a negative active material₂The electrostatic spinning of nano-fibers is carried out byRegulating and controlling relevant technological parameters (spinning flow rate, mass fraction of polymer solution and raw material in spinning solution, solvent proportion and voltage intensity, etc.) of electrospinning process to prepare SnX₂Nanofibers such as SnF₂Nanofibers of SnX₂The nano-fiber can be mixed with carbon materials, particularly graphite carbon materials (such as natural graphite, expanded graphite, artificial graphite and the like, but not limited to graphite materials), and can be used as a negative electrode nano-fiber active material for forming batteries or capacitors of lithium, sodium, potassium, calcium, magnesium, zinc and the like, so that the selection range of the negative electrode material of the batteries or capacitors is widened, and the performance of secondary batteries or capacitors using the negative electrode active material is improved.

Further, compared with the preparation method adopted by D.Narsimulu et al, the biggest advantage of the invention is to provide SnX₂The nanofiber material prepared by the method has surface function flexibility, larger specific surface area and volume ratio and excellent mechanical property, and is SnX prepared based on the electrostatic spinning technology₂The nanofiber material can be mixed with an optional conductive additive to be used as a negative electrode active material of secondary batteries of lithium, sodium, potassium, calcium, magnesium, zinc ions and the like and corresponding capacitors, and the assembled secondary battery shows the battery performance of high capacity and cycling stability, and overcomes the defects that the radius of metal ions (such as sodium ions and potassium ions) is large and the volume is easy to expand in the charging and discharging processes of the battery; substantially relieve similar SnO₂The electrolyte and the electrolyte containing metal salt form metal oxide on the negative electrode, and irreversible phase change occurs, so that the phenomenon of rapid capacity attenuation occurs. The invention provides SnX₂The nanofiber material and the electrostatic spinning preparation process widen the selection range of the battery cathode material. Meanwhile, the preparation method is simple to operate, easy to implement, low in cost and suitable for industrial application.

The term "optional conductive additive" as used herein means that the negative electrode active material may or may not contain a conductive additive. That is, the preparation method can be expressed as: SnX₂Mixing the solution with the polymer solution to obtain polymer gel solutionLiquid, preparation of SnX by electrostatic spinning technology₂A nanofiber material to obtain a negative active material; can also be expressed as: SnX₂Mixing the solution with the polymer solution to obtain polymer gel solution, and preparing SnX by using electrostatic spinning technology₂A nanofiber material of SnX₂The nanofiber material is mixed with a conductive additive to obtain a negative active material.

FIG. 1 shows an embodiment of the present invention providing SnX₂As shown in fig. 1, the electrostatic spinning working principle provided by the present invention is as follows: under the action of the high-voltage power supply 10 of the high-voltage electrostatic field, electrostatic force and surface tension of the electrostatic force jointly act on SnX₂The polymer solution 20, as the electric field intensity increases, the surface charge density of the liquid drop at the end of the capillary increases, the liquid drop changes from a spherical shape to a conical (Taylor cone) Taylor cone 30 at the needle tip, when the electrostatic force is greater than the surface tension to a certain degree, the liquid drop overcomes the surface tension and the viscous force to form a jet flow at the end of the cone, SnX₂The solid nanofiber filaments are deposited on a metal collector 40 such as copper foil.

Through a large number of experimental researches, the invention obtains the appropriate soluble SnX₂The solvent and the proportion thereof select proper polymer solution, ensure the solution viscosity, adjust the influence of environmental parameters such as temperature, humidity, air flow rate and the like, and finally successfully prepare the SnX with excellent performance₂A nanofiber material of₂The proposal of the nanofiber material and the electrostatic spinning preparation process thereof widens the selection range of the cathode material of the battery or the capacitor, provides a new idea for the research of the cathode material of the battery or the capacitor, and provides a new idea for SnX₂The high value application of the nanofiber material widens the road.

In a preferred embodiment of the present invention, the SnX is₂The preparation method of the nanofiber material specifically comprises the following steps:

(1) pretreating, dissolving the SnX sample by using an alcohol solvent and water as a mixed solvent₂Preferably, the ratio of the alcoholic solvent to water is 3: 1, followed by ultrasonic dispersion. At the same time, the polymer is dissolved and treated optionallyThe polymer is selected from PAN (polyacrylonitrile), PVP (polyvinylpyrrolidone), PEO (polyethylene oxide), PVA (polyvinyl alcohol), etc., and its properties are soluble in water and organic solvent, and the polymer is dissolved in deionized water, stirred, and the dissolved SnX is added₂The solution was slowly added to the polymer solution and stirred with a magnetic stirrer until a slightly viscous polymer gel solution was mixed.

(2) Setting electrospinning conditions, ensuring that the distance between a spray head (needle head) and a metal collector is a fixed value within the range of 10-20 cm, adjusting the solution feeding rate to be a fixed value within the range of 0.1-1.0 mL/h, setting the direct-current power supply voltage to be a fixed value within the range of 10-25 kV, obtaining crude nano-fibers by using a collector which can be made of metal foils such as aluminum, copper, tin, zinc, lead and other metal collectors, and then carrying out centrifugal cleaning to obtain a final product SnX₂A nanofiber material.

In addition, SnX₂When X in the nanofiber material is F, Cl or Br respectively, the working principle and the whole operation method are similar, a proper polymer can be selected according to the characteristics of a precursor solution, a solution with proper conductivity and a solvent with certain volatility are selected (the solvent has good volatility, can effectively avoid the generation of beaded fibers and obtain fibers with uniform diameters), and the elasticity, the conductivity and the surface tension of the precursor solution are influenced by adjusting the concentration viscosity of the solution and adjusting environmental parameters (such as temperature, humidity, air flow rate and the like). In addition, corresponding nano-fiber SnF is prepared by adjusting electrospinning operation parameters such as voltage value, fluid flow rate and receiving distance (distance between the tip of the capillary and a collecting screen)₂、SnCl₂Or SnBr₂. The invention is mainly based on SnF₂The preparation of nanofibers is described in further detail by way of example, but it is to be understood that the SnCl can be obtained separately by adjusting the specific operating conditions described above within suitable ranges₂Or SnBr₂。

In a preferred embodiment, SnF₂The preparation method of the nanofiber specifically comprises the following steps:

(1) pretreatment (dissolution of sample): firstly, weighing a certain amount of sample SnF₂Putting the mixture into a mixed solvent for ultrasonic dispersion to obtain SnF₂A solution;

preferably, SnX₂Solutions (e.g. SnF)₂Solution) is a mixed solvent composed of an organic solvent and water, preferably the organic solvent includes at least one of alcohols, ketones, esters or ethers, more preferably the organic solvent is an alcohol organic solvent, more preferably the alcohols are lower alcohols, more preferably the lower alcohols include at least one of methanol, ethanol, propanol, ethylene glycol or butanol, and more preferably the lower alcohols are ethanol. It is to be understood that the present invention is not particularly limited as to the specific type of the above-mentioned organic solvent, as long as it does not limit the object of the present invention. The solvent can be at least one of alcohol, ketone, ester, ether solvent and the like which are commonly used in the field, and can also be other similar solvents, the alcohol solvent is preferably adopted, more preferably ethanol is adopted, and the ethanol and water are mixed to dissolve the sample, so that the dissolving effect is good, the source is wide, the cost is low, and the mixing effect with the polymer solution is better.

Preferably, the mass ratio of the organic solvent to the water is 1-10: 1, preferably 2-4: 1, more preferably 3: 1, typically but not limited to, for example, 1: 1. 2: 1. 3: 1. 4: 1. 5: 1. 6: 1. 7: 1. 8: 1. 9: 1 or 10: 1.

preferably, SnX₂Solutions (e.g. SnF)₂Solution) of SnX₂The concentration of (b) is in the range of 0.05 to 15g/mL, preferably 0.1 to 10g/mL, and typically but not limited to, for example, 0.05g/mL, 0.08g/mL, 0.1g/mL, 0.2g/mL, 0.5g/mL, 1.0g/mL, 1.5g/mL, 2g/mL, 5g/mL, 8g/mL, 10g/mL or 15 g/mL.

Preferably, SnX₂Solutions (e.g. SnF)₂Solution) and inorganic salt including NaCl, KCl, LiCl, FeCl₃、ZnCl₂、CuCl₂Or NaNO₃Preferably NaCl, with SnX₂The mass ratio of (A) to (B) is 0.01-0.5: 1, preferably 0.05-0.1: 1, which may be, for example, typically but not by way of limitation, 0.01: 1. 0.02: 1. 0.05: 1. 0.08: 4. 0.1: 1. 0.2: 1. 0.3: 1. 0.4: 1 or 0.5: 1. in SnX₂The addition of a certain amount of NaCl powder to the solution can reduce the formation of beads in a large range during electrospinning because the addition of salt leads to an increase in the surface charge density of the solution jet, thereby bringing more charge to the jet. As the jet increases, the jet experiences higher tension under the electric field, resulting in smaller beads and finer fiber diameters. But this does not suggest that a high electric field can result in fewer beads and finer fibers.

Preferably, SnX₂Solutions (e.g. SnF)₂Solution) is subjected to ultrasonic dispersion in the preparation process, and the ultrasonic dispersion time is 5-60 min, preferably 30-40 min, and further preferably 30 min.

Dissolving a proper amount of polymer in deionized water, adding a magnetic stirrer at room temperature, and stirring in a fume hood for about 6 hours to obtain a polymer solution;

preferably, the polymer is a polymer that is soluble in both water and an organic solvent, and the polymer preferably includes, but is not limited to, at least one of PAN (polyacrylonitrile), PVP (polyvinylpyrrolidone), PEO (polyethylene oxide), PVA (polyvinyl alcohol), and the like, and further preferably PVP. It is to be understood that the present invention is not particularly limited as to the specific type of the above-mentioned polymer, as long as it does not limit the object of the present invention. The SnF may be at least one of polymers such as PAN, PVP, PEO and PVA, or similar other polymers, preferably PVP₂The solution is mixed with the PVP polymer solution, the viscosity of the solution can be better ensured, the mixing effect is better, and the SnF with more excellent performance can be obtained₂A nanofiber material.

Preferably, the concentration of the polymer in the polymer solution is in the range of 0.01 to 20g/mL, preferably 0.1 to 10g/mL, and more preferably 0.15g/mL, and typically but not limited to, for example, 0.01g/mL, 0.05g/mL, 0.1g/mL, 0.2g/mL, 0.5g/mL, 1.0g/mL, 1.5g/mL, 2g/mL, 5g/mL, 8g/mL, 10g/mL, 15g/mL, or 20 g/mL.

(2) Preparation of gel polymer solution: SnF obtained in the step (1)₂Slowly adding the solution into the PVP polymer solution, adding a magnetic stirring bar, and stirring until the solution is mixedA slightly viscous polymer gel solution was synthesized and some fluidity was observed;

preferably, SnF₂The solution and the PVP polymer solution are mixed and then continuously stirred for about 6 hours.

(3) Electric spinning operation: absorbing 5mL of the polymer gel solution obtained in the step (2) by using an injector, wherein the diameter of a stainless steel needle head is 0.3mm, the distance between the needle head and a metal collector is a fixed value of 10-20 cm under constant temperature and relative humidity, the solution feeding rate is adjusted, the direct-current power supply voltage is set, and then electrostatic spinning operation is carried out;

preferably, the constant temperature and relative humidity is about 25 ℃ at room temperature, and the air relative humidity is about 50% RH;

preferably, the distance between the needle head (spray head) and the collector is 10-20 cm, preferably 12-15 cm, and further preferably 12 cm;

preferably, the solution feeding rate is 0.1-10 mL/h, preferably 0.2-1.0 mL/h, and more preferably 0.2 mL/h;

preferably, the voltage of the direct-current power supply is set to be 10-25 kV, preferably 15-22 kV, and further preferably 22 kV;

preferably, the collector is a metal foil, such as aluminum, copper, tin, zinc, lead, and the like, and more preferably a copper foil collector.

Production of SnX under the preferred electrospinning operating conditions described above₂The nanofiber material can further improve the performance of the nanofiber material, so that the nanofiber material has surface function flexibility, has a large specific surface area and volume ratio and excellent mechanical performance, and can be better applied to a secondary battery or a capacitor to improve the performance of the secondary battery or the capacitor.

(4) Centrifugal cleaning: centrifuging, washing, filtering and drying the fibers collected on the metal collector to obtain SnX₂The nanofiber material is a negative nanofiber active material capable of being assembled into a battery;

preferably, the rotating speed of the centrifugation is 8000-10000 rpm, preferably 8500-9000 rpm;

the centrifugation time is 3-10 min, preferably 5-6 min.

It should be understood that the details of the above preparation method, such as the drying temperature, time, etc., which are not described in detail, are conventional in the art, and can be adjusted by those skilled in the art according to the actual situation, so that the detailed description thereof can be omitted.

In a fifth aspect, in at least one embodiment, there is provided a negative electrode comprising a negative electrode current collector and a negative electrode material comprising the above negative electrode active material or the negative electrode active material prepared by the above method for preparing a negative electrode active material.

It is understood that the negative electrode includes a negative electrode current collector and a negative electrode material including a negative electrode active material, a conductive agent, and a binder. The core of the cathode is that the SnX prepared by the electrostatic spinning technology is used₂A nanofiber material. Specific types of the negative electrode current collector, the conductive agent, and the binder are not particularly limited, and a negative electrode current collector, a conductive agent, and a binder, which are generally used in the art, may be used.

Preferably, the conductive agent includes at least one of conductive carbon black (acetylene black, Super P, Super S, 350G, or ketjen black), conductive carbon spheres, conductive graphite, carbon nanotubes, conductive carbon fibers, graphene, or reduced graphene oxide;

preferably, the binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl cellulose, SBR rubber, or polyolefin (polybutadiene, polyvinyl chloride, polyisoprene, etc.) binders.

Preferably, the negative electrode material comprises, by mass, 60-97 wt% of a negative electrode active material, 1-25 wt% of a conductive agent and 2-15 wt% of a binder; typically, but not by way of limitation, the mass percent of the negative active material may be, for example, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 97%; the mass percentage of the conductive agent may be, for example, 1%, 2%, 3%, 4%, 5%, 8%, 10%, 12%, 15%, 20%, or 25%; the mass percentage of the binder may be, for example, 2%, 3%, 4%, 5%, 6%, 8%, 9%, 10%, 12%, or 15%.

The negative electrode material obtained by adopting the negative electrode active material, the conductive agent and the binder in specific percentage has good comprehensive performance, and can well play the role of the negative electrode material in a secondary battery or a capacitor.

In the negative electrode material, the negative electrode active material may be SnX alone₂The nanofiber material may also be SnX₂The mixture of the nanofiber material and the conductive additive can adopt the same or different substances, and preferably the same substances, as the conductive agent in the anode material. That is, in the process of preparing the negative electrode material, a certain amount of the conductive additive (conductive agent) may be added in advance to the negative electrode active material, or the negative electrode active material, the conductive agent, and the binder may be directly mixed to prepare the negative electrode material.

It is understood that the negative electrode current collector of the present invention may employ one commonly used in the art, including but not limited to, one of aluminum, copper, tin, zinc, lead, antimony, cadmium, gold, bismuth, germanium, etc., or an alloy containing at least any one of the foregoing metals, or a composite containing at least any one of the foregoing metals; preferably, the negative electrode current collector is a copper foil.

In a sixth aspect, there is provided in at least one embodiment a secondary battery or capacitor comprising the above-described anode, cathode, separator interposed between the anode and the cathode, and electrolyte.

It should be noted that the negative electrode according to the present invention may be equipped with secondary batteries of different systems, such as lithium, sodium, potassium, calcium, magnesium, zinc ion, etc. secondary batteries and corresponding capacitors thereof, but is not limited to such, and modifications and replacements of conditions thereof. That is, various secondary batteries and capacitors assembled based on the negative electrode active material prepared according to the present invention are protected.

It is to be understood that the negative electrode active material, negative electrode of the present invention are applicable to various types of secondary batteries, capacitors. Fig. 2 shows a schematic structural diagram of a secondary battery according to an embodiment of the present invention, which is a potassium bi-ion battery assembled with a negative electrode nanofiber active material. SnX of the invention₂The nano-fiber material can be used as the cathode active material of secondary batteries of lithium, sodium, potassium, calcium, magnesium, zinc ions and the like and corresponding capacitors. Taking a potassium-based bi-ion battery as an example, referring to fig. 2, the secondary battery includes a negative electrode current collector (1), a battery negative electrode active material (2), an electrolyte (3), a separator (4), a battery positive electrode active material (5), and a positive electrode current collector (6). Further, the negative electrode of the secondary battery comprises a negative electrode current collector and a negative electrode active material, wherein the negative electrode current collector comprises a metal, a metal alloy or a metal composite conductive material, and the negative electrode active material layer comprises a material capable of allowing potassium ions to be freely embedded and removed, wherein the negative electrode active material is the above negative electrode active material. The electrolyte comprises a solvent and an electrolyte, and the electrolyte is a potassium salt. The positive electrode of the battery comprises a positive electrodeThe negative electrode comprises a current collector and a negative electrode active material layer, wherein the negative electrode current collector comprises a metal, metal alloy or metal compound conductive material, and the negative electrode active material layer comprises a material which can allow anions forming potassium salt to be freely adsorbed and desorbed.

In the potassium-based double-ion battery, the positive current collector comprises one or an alloy of carbon-coated aluminum foil, copper foil, iron foil, tin foil, zinc foil, nickel foil, titanium foil and manganese foil or a compound of any one of the metals or an alloy of any one of the metals; preferably, the positive electrode current collector is a carbon-coated aluminum foil. The positive electrode active material includes one or more of materials having a layered structure such as a carbon material, prussian blue and the like, a phosphorus compound, and the like; preferably, the carbon material is preferably a graphite-based carbon material.

It should be noted that the specific types of the positive electrode, the electrolyte, and the separator in the present invention are not particularly limited, and the positive electrode, the electrolyte, and the separator commonly used in the art may be used.

According to the invention, the metal foil of the battery negative current collector is one of aluminum, copper, tin, zinc, lead, antimony, cadmium, gold, bismuth and germanium or the alloy or the composite material; preferably a copper foil. The negative electrode active material is the above-mentioned negative electrode active material, i.e., the negative electrode active material containing the SnX2 nanofiber material.

According to the invention, the battery positive electrode current collector comprises one of a carbon-coated aluminum foil, a carbon-coated copper foil, a carbon-coated iron foil, a carbon-coated tin foil, a carbon-coated zinc foil, a carbon-coated nickel foil, a carbon-coated titanium foil and a carbon-coated manganese foil, or an alloy at least containing any one of the metals, or a composite at least containing any one of the metals; preferably, the positive electrode current collector is a carbon-coated aluminum foil.

The positive active material is selected from one or more of carbon material, sulfide, nitride and oxide with a layered structure;

wherein the carbon material is selected from one or more of activated carbon, mesocarbon microbeads graphite, natural graphite, expanded graphite, glassy carbon, carbon-carbon composite materials, carbon fibers, hard carbon, porous carbon, highly-oriented graphite, carbon black, carbon nanotubes and graphene; the sulfide is selected from one or more of molybdenum disulfide, tungsten disulfide, vanadium disulfide, titanium disulfide, iron disulfide, ferrous sulfide, nickel sulfide, zinc sulfide, cobalt sulfide and manganese sulfide; the nitride is selected from one or more of hexagonal boron nitride and carbon-doped hexagonal boron nitride; the oxide is selected from one or more of molybdenum trioxide, tungsten trioxide, vanadium pentoxide, vanadium dioxide, titanium dioxide, zinc oxide, copper oxide, nickel oxide and manganese oxide or a compound thereof.

The positive active material layer provided by the embodiment of the invention further comprises a conductive agent and a binder, wherein the content of the positive active material is 60-90 wt%, preferably 80 wt%, the content of the conductive agent is 5-30 wt%, preferably 10 wt%, and the content of the binder is 5-10 wt%, preferably 10 wt%. Meanwhile, the conductive agent and the binder are not particularly limited and may be those commonly used in the art. For example, the conductive agent may be one or more of conductive carbon black, conductive carbon spheres, conductive graphite, carbon nanotubes, conductive carbon fibers, graphene, reduced graphene oxide. The binder can be one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl cellulose, SBR rubber and polyolefin.

Preferably, the conductive agent is conductive carbon black, and the binder is polytetrafluoroethylene (dissolved by adding NMP nitrogen-methyl pyrrolidone).

According to the present invention, the solvent in the electrolytic solution is not particularly limited as long as the solvent can dissociate the electrolyte into cations and anions, and the cations and anions can freely migrate. For example, the solvent in the embodiment of the present invention includes organic solvents such as esters, sulfones, ethers, nitriles, or ionic liquids. Specifically, Propylene Carbonate (PC), Ethylene Carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), Ethyl Methyl Carbonate (EMC), Methyl Formate (MF), Methyl Acetate (MA), N-Dimethylacetamide (DMA), fluoroethylene carbonate (FEC), Methyl Propionate (MP), Ethyl Propionate (EP), Ethyl Acetate (EA), γ -butyrolactone (GBL), Tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), 1, 3-Dioxolane (DOL), 4-methyl-1, 3-dioxolane (4MeDOL), Dimethoxymethane (DMM), 1, 2-Dimethoxypropane (DMP), triethylene glycol dimethyl ether (DG), dimethyl sulfone (MSM), dimethyl ether (DME), Ethylene Sulfite (ES), Propylene Sulfite (PS), dimethyl sulfite (DMS), diethyl sulfite (DES), DES, Crown ether (12-crown-4), 1-ethyl-3-methylimidazole-hexafluorophosphate, 1-ethyl-3-methylimidazole-tetrafluoroborate, 1-ethyl-3-methylimidazole-bistrifluoromethylsulfonyl imide salt, 1-propyl-3-methylimidazole-hexafluorophosphate, 1-propyl-3-methylimidazole-tetrafluoroborate, 1-propyl-3-methylimidazole-bistrifluoromethylsulfonyl imide salt, 1-butyl-1-methylimidazole-hexafluorophosphate, 1-butyl-1-methylimidazole-tetrafluoroborate, 1-butyl-1-methylimidazole-bistrifluoromethylsulfonyl imide salt, N-butyl-N-methylpyrrolidine-bistrifluoromethylsulfonyl imide salt, 1-butyl-1-methylpyrrolidine-bistrifluoromethylsulfonyl imide salt, N-methyl-N-propylpyrrolidine-bistrifluoromethylsulfonyl imide salt, One or more of N-methyl, propyl piperidine-bis (trifluoromethyl) sulfonyl imide salt and N-methyl, butyl piperidine-bis (trifluoromethyl) sulfonyl imide salt.

Preferably, the electrolyte solvent is Ethylene Carbonate (EC) and/or dimethyl carbonate (DMC).

According to the present invention, potassium salts as electrolytes are also not particularly limited as long as they can be dissociated into cations and anions, and include, for example, potassium hexafluorophosphate, potassium chloride, potassium fluoride, potassium sulfate, potassium carbonate, potassium phosphate, potassium nitrate, potassium difluoroborate, potassium pyrophosphate, potassium dodecylbenzenesulfonate, potassium dodecylsulfate, tripotassium citrate, potassium metaborate, potassium borate, potassium molybdate, potassium tungstate, potassium bromide, potassium nitrite, potassium iodate, potassium iodide, potassium silicate, potassium lignosulfonate, potassium oxalate, potassium aluminate, potassium methanesulfonate, potassium acetate, potassium dichromate, potassium hexafluoroarsenate, potassium tetrafluoroborate, potassium perchlorate, potassium trifluoromethanesulfonimide (KTFSI), KCF, potassium tetrafluoroborate, potassium trifluoromethanesulfonimide (KTFSI), potassium trifluoromethanesulfonimide (KCF), potassium fluoride, potassium carbonate, potassium salt of potassium methanesulfonate, potassium nitrate, potassium citrate, potassium hydrogen phosphate, potassium dodecylbenzenesulfona₃SO₃、KN(SO₂CF₃)₂One or more of the above, and the concentration range is 0.1-10 mol/L.

Preferably, the electrolyte potassium salt is potassium hexafluorophosphate.

According to the present invention, the separator is not particularly limited, and a common separator existing in the art may be used. For example, the used separator is composed of an insulating porous polymer film or an inorganic porous film, and may be one or more of a porous polypropylene film, a porous polyethylene film, a porous composite polymer film, a glass fiber paper or a porous ceramic separator.

Preferably, the separator is a fiberglass paper.

In a sixth aspect, there is provided in at least one embodiment a method of manufacturing a secondary battery or capacitor, comprising assembling the negative electrode, the electrolyte, the separator, and the positive electrode as described above to obtain a secondary battery;

The method for manufacturing a potassium-based bi-ion battery will be described in detail by taking a specific method for manufacturing a potassium-based bi-ion battery as an example.

The potassium-based double-ion secondary battery comprises a battery cathode, electrolyte, a diaphragm and a battery anode, wherein the battery cathode comprises a cathode current collector and a cathode active material, and the cathode active material is SnX₂A polymeric nanofiber material. The electrolyte comprises an electrolyte and a solvent, wherein the electrolyte comprises one of potassium salts; the solvent comprises one or more of ester, sulfone, ether organic solvents or ionic liquid. Preferably, the electrolyte potassium salt is potassium hexafluorophosphate, and the electrolyte solvent is ethylene carbonate and dimethyl carbonate. The preparation process comprises the following steps:

(1) preparing a battery cathode: weighing the negative active material, the conductive agent and the binder according to a certain proportion, adding the negative active material, the conductive agent and the binder into a proper solvent, and fully mixing to obtain uniform slurry to prepare a negative active material layer; cleaning a negative current collector, uniformly coating the negative active material layer on the surface of the negative current collector, and cutting after the negative active material layer is completely dried to obtain the battery negative electrode with the required size;

(2) preparing an electrolyte: weighing a certain amount of potassium salt electrolyte, adding the potassium salt electrolyte into a corresponding solvent, and fully stirring and dissolving;

(3) preparing a diaphragm: cutting the diaphragm into required size, and cleaning;

(4) preparing a battery anode, weighing an anode active material, a conductive agent and a binder according to a certain proportion, adding into a proper solvent, and fully mixing to obtain uniform slurry to prepare an anode active material layer; cleaning a positive current collector, uniformly coating the positive active material layer on the surface of the positive current collector, and cutting after the positive active material layer is completely dried to obtain a battery positive electrode with a required size;

(5) and assembling the battery cathode, the electrolyte, the diaphragm and the battery anode to obtain the potassium-based double-ion secondary battery.

It should be noted that although the above steps (1) to (4) describe the operations of the preparation method of the present invention in a specific order, this does not require or imply that these operations must be performed in this specific order. The preparation of steps (1) to (4) may be performed simultaneously or in any order.

It is to be understood that the method for manufacturing the capacitor may be assembled by a method well known to those skilled in the art with reference to the method for manufacturing the secondary battery described above, and the present invention will not be described in detail herein.

The present invention will be further described with reference to specific examples, comparative examples and the accompanying drawings.

Example 1

1. Negative electrode active material

An anode active material comprising SnF₂A nanofiber material.

SnF₂The preparation of the nanofiber material comprises the following steps:

(1) pretreatment (dissolution of sample): firstly, 1.5g of SnF sample is taken₂Putting the mixture into a reactor with the mass ratio of 3: 1, ultrasonically dispersing for 30min in a mixed solvent of ethanol and water; in SnF₂0.1g NaCl powder is added into the solution to reduce the formation of large-range beads during electrospinning;

dissolving 4.5g of polymer PVP in 30mL of deionized water, adding a magnetic stirrer at room temperature, and stirring for 6 hours in a fume hood;

(2) preparation of gel polymer solution: SnF obtained in the step (1)₂Slowly adding the solution into the PVP polymer solution, adding a magnetic stirring bar, stirring until the mixture is mixed into a light viscous polymer gel solution, continuously stirring for 6 hours, and observing that the solution has certain fluidity;

(3) electric spinning operation: sucking 5mL of the polymer gel solution obtained in the step (2) by using a syringe, wherein the diameter of a stainless steel needle is 0.3mm, the air relative humidity is 50% RH at room temperature (about 25 ℃), the distance between the needle and a metal collector is 12cm, the solution feed rate is adjusted to 0.2mL/h, a direct-current power supply is set to 22kV, and the collector can collect fibers by using a copper foil metal collector;

(4) centrifugal cleaning: centrifuging, washing, filtering and drying the fibers collected on a copper foil collector to obtain the battery-assembled nano-fiber active material SnF₂A nanofiber material.

2. Negative electrode

A negative electrode includes a negative electrode current collector and a negative electrode material including a negative electrode active material, a conductive agent, and a binder.

The preparation of the negative electrode includes: 0.8g of SnF₂Adding a nanofiber material (a negative electrode active material), 0.1g of acetylene carbon black and 0.1g of polyvinylidene fluoride into 2mL of a nitrogen methyl pyrrolidone solution, and fully grinding to obtain uniform slurry; and cleaning the copper foil of the negative current collector, uniformly coating the slurry on the surface of the copper foil, performing vacuum cleaning, drying to obtain a pole piece, cutting the pole piece into a wafer material layer with the diameter of 12mm, and compacting to obtain the battery negative electrode for later use.

3. Potassium-based dual-ion battery

A potassium-based double-ion battery comprises a battery negative electrode, electrolyte, a diaphragm and a positive electrode, wherein the negative electrode comprises a negative electrode current collector and a negative electrode material, and the negative electrode is the negative electrode prepared by the steps.

The preparation method of the potassium-based double-ion battery comprises the following steps:

(1) preparing an electrolyte: weighing 0.7363g of potassium hexafluorophosphate, adding the potassium hexafluorophosphate into a mixed solvent of 5mL of ethylene carbonate (3.3045g) and dimethyl carbonate (2.6725g), stirring until the potassium hexafluorophosphate is completely dissolved, adding a potassium salt molecular sieve, and fully and uniformly stirring to obtain an electrolyte for later use;

(2) preparing a diaphragm: cutting the glass fiber film into a wafer with the diameter of 16mm, and using the wafer as a diaphragm for later use;

(3) preparing a battery positive electrode: adding 0.8g of Expanded Graphite (EG), 0.1g of acetylene black and 0.1g of polytetrafluoroethylene into 2mL of nitrogen methyl pyrrolidone solution, and fully grinding to obtain uniform slurry; and cleaning the positive current collector carbon-coated aluminum foil, uniformly coating the slurry on the surface of the carbon-coated aluminum foil, and drying in vacuum. Cutting the dried electrode slice into a wafer material layer with the diameter of 10 mm; and compacting to obtain the positive electrode of the battery for later use.

Assembling the battery: and (3) setting the box body pressure to be 1-5 in a glove box protected by inert gas, tightly stacking the prepared cathode, the diaphragm and the anode in sequence, dripping electrolyte to completely soak the diaphragm, and packaging the stacked part into a button cell shell to finish cell assembly.

Examples 2 to 8

Examples 2 to 8 are different from example 1 in the specific operating conditions in the preparation method of the negative active material, SnF in examples 1 to 8₂The raw materials for the preparation of the nanofiber material and the processing conditions are shown in table 1 and table 2, respectively.

Table 1 preparation of negative active materials in examples 1 to 8

Table 2 treatment conditions in the preparation methods of negative active materials in examples 1 to 8

The below-described electrospinning treatment conditions for the nanofiber materials of examples 9-17 are shown in table 3, and the nanofiber active materials prepared in examples 10-17 were different from example 9 only in temperature, solution feeding rate, humidity, voltage and acceptance distance, and the remaining conditions and steps were the same.

Table 3 processing conditions in preparation methods of negative active materials in examples 9 to 17

Example 9

The difference from example 1 is that: and a negative electrode active material.

The anode active material provided by the embodiment comprises SnCl₂A nanofiber material.

SnCl₂The preparation of the nanofiber material comprises the following steps:

(1) pretreatment (dissolution of sample): firstly, 1.5g of SnCl sample is taken₂·2H₂Putting O into a reactor with the mass ratio of 3: 1, ultrasonically dispersing for 30min in a mixed solvent of ethanol and water; in SnCl₂0.1g NaCl powder is added into the solution to reduce the formation of large-range beads during electrospinning;

dissolving 4g of polymer PVP in 40mL of deionized water, adding a magnetic stirrer at room temperature, and stirring for 6 hours in a fume hood;

(2) preparation of gel polymer solution: SnCl obtained in the step (1)₂Slowly adding the solution into the PVP polymer solution, adding a magnetic stirring bar, stirring until the mixture is mixed into a light viscous polymer gel solution, continuously stirring for 6 hours, and observing that the solution has certain fluidity;

(4) centrifugal cleaning: centrifuging, washing, filtering and drying the fibers collected on a copper foil collector to obtain the productBattery-assembled nanofiber active material-SnCl₂A nanofiber material.

The rest is the same as in example 1.

Example 18

The present example is different from example 1 in the preparation of a secondary battery.

In this example, the battery positive electrode: 0.8047g of natural graphite, 0.1068g of conductive graphite and 0.1052g of polytetrafluoroethylene are added into 2mL of nitrogen methyl pyrrolidone solution;

battery negative pole: 0.8023g of SnF obtained in example 2₂Adding a nanofiber material, 0.1089g of super P conductive carbon spheres and 0.1028g of polytetrafluoroethylene into 2mL of nitrogen methyl pyrrolidone solution; the negative current collector is aluminum foil;

electrolyte solution: 2.2787g of potassium chloride was weighed and added to 5mL of a mixed solvent of ethylene carbonate (2.203g), dimethyl carbonate (1.7817g) and ethyl methyl carbonate (1.683 g);

a diaphragm: a porous polypropylene separator.

Example 19

In this example, the battery positive electrode: 0.8071g of crystalline flake graphite, 0.1054g of conductive carbon spheres and 0.1g of polytetrafluoroethylene are added into 2mL of nitrogen methyl pyrrolidone solution;

battery negative pole: 0.8027g of SnF obtained in example 3₂Adding a nanofiber material, 0.1074g of super P conductive carbon spheres and 0.1028g of polytetrafluoroethylene into 2mL of nitrogen methyl pyrrolidone solution; the negative current collector is a nickel sheet;

electrolyte solution: 2.8352g of potassium difluorooxalato borate was weighed and added to 5mL of a mixed solvent of ethylene carbonate (2.203g) and propylene carbonate (2.203 g);

a diaphragm: a composite glass fiber membrane.

Example 20

In this example, the battery positive electrode: 0.8045g of carbon nano tube, 0.1036g of acetylene black and 0.1087g of polyvinyl alcohol are added into 2mL of nitrogen methyl pyrrolidone solution;

battery negative pole: 0.8073g of SnF obtained in example 4₂Adding a nanofiber material, 0.1083g of conductive graphite and 0.1054g of polytetrafluoroethylene into 2mL of nitrogen methyl pyrrolidone solution; the negative current collector is an iron sheet;

electrolyte solution: 2.8352g of potassium fluoride is weighed and added into a mixed solvent of 5mL of ethylene carbonate (2.3502g) and dimethyl ether (2.3513 g);

a diaphragm: a porous polyethylene film.

Example 21

In this example, the battery positive electrode: 0.8084g of graphene, 0.1032g of conductive carbon fibers and 0.1051g of hydroxymethyl cellulose are added into 2mL of nitrogen methyl pyrrolidone solution;

battery negative pole: 0.8075g of SnF obtained in example 5₂Adding a nanofiber material, 0.1017g of conductive carbon black and 0.1043g of polytetrafluoroethylene into 2mL of nitrogen methyl pyrrolidone solution; the negative current collector is a zinc sheet;

electrolyte solution: 1.9453g of potassium phosphate was weighed and added to a mixed solvent of 5mL of ethylene carbonate (2.0743g), propylene carbonate (2.0745g) and 5% fluoroethylene carbonate;

a diaphragm: a porous ceramic diaphragm.

Example 22

In this example, the battery positive electrode: 0.8136g of carbon-carbon composite material, 0.102g of reduced graphene oxide and 0.1g of polyolefin are added into 2mL of nitrogen methyl pyrrolidone solution;

battery negative pole: 0.802g of SnF obtained in example 6₂Adding a nanofiber material, 0.1g of conductive graphite and 0.1g of polytetrafluoroethylene into 2mL of nitrogen methyl pyrrolidone solution; the negative current collector is a zinc sheet;

electrolyte solution: 2.4371g of potassium citrate is weighed and added into a mixed solvent of 5mL of ethylene carbonate (2.0743g) and dimethyl carbonate (2.0698 g);

a diaphragm: a composite polymeric film.

Example 23

The present embodiment provides a sodium-based bi-ion battery.

A sodium-based dual-ion battery comprises a battery cathode, electrolyte, a diaphragm and an anode.

The preparation method of the sodium-based dual-ion battery comprises the following steps:

(1) preparing an electrolyte: weighing 0.8401g of sodium hexafluorophosphate, adding the sodium hexafluorophosphate into 5mL of a mixed solvent of ethylene carbonate (2.203g), dimethyl carbonate (1.7817g) and potassium carbonate ethyl ester (1.6834g), stirring until the sodium hexafluorophosphate is completely dissolved, adding a sodium salt molecular sieve, and fully and uniformly stirring to obtain an electrolyte for later use;

(4) A negative electrode includes a negative electrode current collector and a negative electrode material including a negative electrode active material, a conductive agent, and a binder.

Preparing a battery cathode: 0.8083g of SnF obtained in example 1₂Adding a nanofiber material (a negative electrode active material), 0.1025g of acetylene black and 0.1047g of polyvinylidene fluoride into 2mL of N-methyl pyrrolidone solution, and fully grinding to obtain uniform slurry; cleaning a tin foil of a negative current collector, uniformly coating the slurry on the surface of the tin foil, performing vacuum cleaning, drying to obtain a pole piece, cutting the pole piece into a wafer material layer with the diameter of 12mm, and compacting to obtain a battery negative electrode for later use

Example 24

The present embodiment provides a sodium-based bi-ion battery.

A sodium-based bi-ion battery was prepared, differing from example 23 in that:

in this example, the battery positive electrode: 0.8021g of carbon fiber, 0.1037g of reduced graphene oxide and 0.1025g of polyolefin are added into 2mL of nitrogen methyl pyrrolidone solution, and the positive current collector is a carbon-coated aluminum foil;

battery negative pole: 0.8034g of SnF obtained in example 6₂Adding a nanofiber material, 0.1036g of conductive carbon black and 0.1051g of polytetrafluoroethylene into 2mL of nitrogen methyl pyrrolidone solution; the negative current collector is tin foil;

electrolyte solution: 0.7063g of sodium perchlorate is weighed and added into a mixed solvent of 5mL of ethylene carbonate (2.0743g) and dimethyl carbonate (2.0698 g);

a diaphragm: glass fiber paper.

Example 25

The present embodiment provides a sodium-based bi-ion battery.

A sodium-based bi-ion battery was prepared, differing from example 23 in that:

in this example, the battery positive electrode: 0.8032g of carbon fiber, 0.1094g of reduced graphene oxide and 0.1042g of polyolefin are added into 2mL of nitrogen methyl pyrrolidone solution, and the positive current collector is a carbon-coated aluminum foil;

battery negative pole: 0.8023g of SnF obtained in example 6₂Adding a nanofiber material, 0.1028g of conductive carbon black and 0.1073g of polytetrafluoroethylene into 2mL of nitrogen methyl pyrrolidone solution; the negative current collector is tin foil;

electrolyte solution: 1.4057g NaTFSI (trifluoromethyl xanthimide) was weighed into 5mL of Ethylene Carbonate (EC)2.2314 g: 2.0472g of dimethyl carbonate (DMC): ethyl Methyl Carbonate (EMC) (2: 3: 2)1.6845 g;

a diaphragm: a nonwoven fabric.

Example 26

The present embodiment provides a sodium-based bi-ion battery.

A sodium-based bi-ion battery was prepared, differing from example 23 in that:

in this example, the battery positive electrode: 0.8019g of carbon fiber, 0.1035g of reduced graphene oxide and 0.1016g of polyolefin are added into 2mL of nitrogen methyl pyrrolidone solution, and the positive current collector is a carbon-coated aluminum foil;

battery negative pole: 0.8027g of SnF obtained in example 6₂Adding a nanofiber material, 0.1018g of conductive carbon black and 0.1039g of polytetrafluoroethylene into 2mL of nitrogen methyl pyrrolidone solution; the negative current collector is tin foil;

electrolyte solution: 1.743g NaFSI (sodium bis fluorosulfonylimide) was weighed into 5mL of ethyl methyl carbonate (2.548 g): sulfolane (1.032g) ═ 5: 1, a mixed solvent;

a diaphragm: a porous ceramic diaphragm.

Comparative example 1

The present comparative example is different from example 1 only in the negative active material.

In the comparative example, the negative active material is K prepared by using Prussian blue analogue and transition element as the conventional negative active material_0.09Ni[Fe(CN)₆]_0.71A rigid material. Wherein the battery negative electrode comprises a negative electrode current collector and a negative electrode active material.

Preparing a battery cathode: weighing 0.8427g K_0.09Ni[Fe(CN)₆]_0.71Adding the material, 0.1g of conductive carbon black and 0.1g of polytetrafluoroethylene into 2mL of nitrogen methyl pyrrolidone solution; fully grinding to obtain uniform slurry; and cleaning the tin foil of the negative current collector, uniformly coating the slurry on the surface of the tin foil, performing vacuum cleaning, drying to obtain a pole piece, cutting the pole piece into a wafer material layer with the diameter of 12mm, and compacting to obtain the battery negative electrode for later use.

The remaining steps were performed using materials and procedures consistent with those of example 1, while comparative energy storage performance was tested and compared to those of example 1.

Comparative example 2

In the comparative example, the negative active material was the conventional one, and Sb was used₂S₃The nano composite material is used as a negative active material of the potassium double-ion battery.

The preparation of the negative electrode includes: 0.8gSb₂S₃Adding the nano composite material (cathode active material), 0.1g of acetylene carbon black and 0.1g of polyvinylidene fluoride into 2mL of nitrogen methyl pyrrolidone solution, and fully grinding to obtain uniform slurry; and cleaning the copper foil of the negative current collector, uniformly coating the slurry on the surface of the copper foil, performing vacuum cleaning, drying to obtain a pole piece, cutting the pole piece into a wafer material layer with the diameter of 12mm, and compacting to obtain the battery negative electrode for later use.

Performance testing

The above examples and comparative secondary batteries were tested for performance, including specific capacity, energy density, and cycling performance. The test method comprises the following steps: placing the button cell assembled in a glove box at a constant temperature of 28 ℃ in a constant temperature test system of a cell room for testing, setting test conditions, 1, discharging to a specified termination voltage (generally 3.0V) at a constant current of 0.5C multiplying power, and charging to the termination voltage (generally 4.2V) at a constant current of 0.5C multiplying power; 2. and (3) ensuring that the circulation is carried out at the ambient temperature of 25 ℃, the battery is not more than 1h when the battery is placed for charging and discharging and electricity-proof and charging, and circulating according to the setting conditions of the previous two steps until the discharge capacity is attenuated to be lower than 70 percent of the rated capacity. The test results are shown in Table 4.

Table 4 results of performance test of secondary batteries of examples and comparative examples

As can be seen from table 4, the potassium-based bi-ion battery obtained in example 1 is the most excellent in electrochemical performance, has higher energy density and specific capacity, and has a long cycle life. The electrochemical performance of the potassium-based bi-ion battery obtained by adopting different negative electrode active materials is different, the specific capacity of the potassium-based bi-ion battery is higher when the negative electrode active material prepared in the embodiment 1 is adopted, and compared with the other two conventional negative electrode active materials, the potassium-based bi-ion battery can still maintain 95% of capacity after 300 cycles, and the coulombic efficiency is more than 94%

In addition, the data in the table show that the specific capacity of the potassium bi-ion battery obtained by adopting the expanded graphite as the positive electrode active material of the battery is higher than that of the potassium bi-ion battery obtained by adopting other carbon materials as the positive electrode active material. The materials of the separators used in the batteries are different, and the electrochemical properties of the obtained secondary batteries are slightly different. The battery electrolyte uses different solvent materials and proportions thereof, and the obtained secondary battery has larger difference of electrochemical properties.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. SnX₂The preparation method of the nano-fiber material is characterized in that the SnX₂Wherein X is a halogen element, said process comprising the steps of:

SnX₂The solution is mixed with the polymer solution,obtaining polymer gel solution, and preparing SnX by electrostatic spinning₂A nanofiber material;

preferably, said X is F, Cl or Br, preferably F.

2. The SnX of claim 1₂The preparation method of the nano-fiber material is characterized in that the SnX₂The solvent in the solution is a mixed solvent composed of an organic solvent and water, preferably the organic solvent comprises at least one of alcohols, ketones, esters or ethers, further preferably the organic solvent is an alcohol organic solvent, further preferably the alcohol is a lower alcohol, further preferably the lower alcohol comprises at least one of methanol, ethanol, propanol, ethylene glycol or butanol, further preferably the lower alcohol is ethanol;

3. Snx according to claim 1 or 2₂Nano fiberThe preparation method of the fiber material is characterized in that in the electrostatic spinning process, the voltage is 10-25 kV, preferably 15-22 kV;

4. SnX according to any of claims 1 to 3₂SnX prepared by preparation method of nanofiber material₂A nanofiber material.

5. Snx according to any of claims 1 to 3₂SnX obtained by preparation method of nanofiber material₂Nanofiber material or SnX of claim 4₂Use of nanofiber materials as negative active materials in secondary batteries or capacitors.

6. An anode active material comprising the SnX of any one of claims 1 to 3₂SnX obtained by preparation method of nanofiber material₂Nanofiber material or SnX of claim 4₂A nanofiber material.

7. The negative electrode active material according to claim 6, further comprising a conductive additive;

8. A negative electrode comprising a negative electrode current collector and a negative electrode material comprising the negative electrode active material according to claim 6 or 7;

9. A secondary battery or capacitor comprising the negative electrode according to claim 8, a positive electrode, a separator interposed between the negative electrode and the positive electrode, and an electrolytic solution;

10. A method for producing a secondary battery or a capacitor, comprising assembling the negative electrode according to claim 8, an electrolyte, a separator, and a positive electrode to obtain a secondary battery;

alternatively, a capacitor is obtained by assembling the negative electrode according to claim 8, an electrolyte, a separator, and a positive electrode.